Pull cable system

ABSTRACT

A pull cable system, includes a cable for transmitting a tensile force, a flexible tube for accommodating the cable, and a casing surrounding the tube for absorbing a pressure force. The casing is composed of a plurality of form-parts so joined to one another as to form a continuous axial passageway which is defined by an inside dimension. The form-parts are so configured that abutting end faces between successive form-parts have a complementary configuration to thereby enable a disposition of the casing along an arcuate path, with the tube being defined by an outside dimension corresponding to the inside dimension of the passageway.

REFERENCE TO RELATED APPLICATION

This is a continuation of Application Ser. No. 08/973,232, filed Jul.20, 1998, now U.S Pat. No. 625,175 which was the National Stage ofInternational Application No. PCT/DE96/01801, filed Sept. 19, 1996.

FIELD OF THE INVENTION

The invention relates to a pull cable system of a type having a cablefor transmitting a pull force and a housing enclosing the cable forabsorbing a pressure force, whereby the housing is comprised of aplurality of form-parts so joined to one another as to form a continuousaxial throughbore and to enable an arcuate disposition of the housing.

BACKGROUND OF THE INVENTION

The so-called Bowden pull wire that basically consists of a coiled steelwire casing and is traversed by a pull cable transmitting pull forces ina flexible manner without deflection rollers, compensating holders andsupports is preferably used for operating the brakes or switching thegears of a bike.

The disadvantage of the Bowden pull wire is its coiled steel wireconstruction. When the wire is disposed in a curve, there are twodifferently stretched lengths to be compensated by forming slits at theouter radius by means of the resiliently coiled steel wire construction.When the pull cable is actuated, the compensating force can be supportedonly at the inner radius, which has the effect of pulling the Bowdenpull wire into a stretched position. This can be prevented by the pullcable imposing this forced position. The result is a high frictionresistance. The stronger the pull cable is being drawn, the larger isthe friction resistance, the more ineffective is the force transmission,which presents a major disadvantage with regard to braking operations.

The variation in lengths occurring when bending the pull cable presentssuch a disadvantage that the Bowden pull wire is hardly suited forprecise chain or hub gear shifting.

A narrow disposition of curves is not possible, which requires anunnecessary addition of length of the Bowden pull wire and thus causeshigher costs, provides a disadvantageous optical appearance and longpaths and thus hardly allows controlled dispositions.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved pullcable system in which the friction resistance is minimized and whichexhibits a better directional stability, a much narrower andtension-free disposition in curves, a reduction of the contact surfacesof the pull cable by 75% and a removal of sliding restraints, as well asbetter armoring and sealing against outer influences.

According to the present invention, this object is solved by a pullcable system which includes a cable for transmitting a tensile force, aflexible tube for accommodating the cable, and a casing surrounding thetube for absorbing a pressure force, whereby the housing is composed ofa plurality of congruent form-parts so joined to one another as to forma continuous axial passageway which is defined by an inside dimension,with the form-parts being so configured that abutting end faces betweensuccessive form-parts have a complementary configuration to therebyenable a disposition of the housing along an arcuate path, wherein thetube is defined by an outside dimension corresponding to the insidedimension of the throughbore.

Preferably, each of the form-parts has opposite end faces, with one ofthe end faces having a concave configuration and the other one of theend faces having a convex configuration. Thus, in accordance with thepresent invention, the coiled steel wire casing utilized in aconventional Bowden cable is replaced by joined complementary form-partswhich permit transmission of great pressure forces by way of a ball panconfiguration of adjoining end faces of successive form-parts.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features and advantages of the presentinvention will now be described in more detail with reference to theaccompanying drawing in which:

FIG. 1 is a general, partially sectional illustration of a firstembodiment of a pull cable system according to the present invention;

FIG. 2 is a cross sectional view of the pull cable system of FIG. 1taken along a plane perpendicular to the bore of the form-part;

FIG. 3 is a cutaway view of the pull cable system of FIG. 1;

FIG. 4 is a general illustration of a second embodiment of a pull cablesystem according to the present invention;

FIG. 5 is a partially cutaway view of the pull cable system of FIG. 4;

FIG. 6 is a general illustration of a third embodiment of a pull cablesystem according to the present invention showing first and second typeform parts, the fist type form part having a cylindrical collar;

FIGS. 7 to 10 shows side views of form-parts having formed thereindifferent configurations of an axial throughbore;

FIG. 11 is a general illustration of a frame assembly containing acurved arrangement of a pull cable system according to the presentinvention;

FIG. 11.1 is a rear section view in a vertical plane of the frameassembly of FIG. 11;

FIG. 11.2 is a front section view in a vertical plane of the frameassembly of FIG. 11;

FIG. 12 is a general illustration of a frame tube accommodating a pullcable system, in diagonal extension, according to the present invention;

FIG. 12.1 is a cutaway side view of the pull cable system of FIG. 12;

FIG. 12.2 is a cutaway top view of the pull cable system of FIG. 12; and

FIG. 13 is a cutaway view, in cross section, of an attachment of a pullcable system to a frame assembly.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawing, and in particular to FIGS. 1 to 3, there areshown general, partially sectional illustrations of a first embodimentof a pull cable system according to the present invention, including aplurality of form-parts 1 joined to one another in-end-to-endrelationship and threaded on a flexible support tube C. Each of theform-parts 1 has one end face to define a support surface 2 of a convexspherical curvature, while the opposite end face is configured as aconcave opening 3 in the form of a ball pan being congruent to thesupport surface 2. The joined form-parts 1 fit congruently surface 2 insurface 3, which allows a narrow disposition of curves with littlefriction, as the different lengths are compensated by the sphericalshape. Thus, the form-parts 1 can be deflected in central direction butcan be lined up along the support tube C to exhibit a continuous curvedpath.

The form-parts 1 are provided interiorly with a bore 4 so that thearrangement of successive form-parts 1 provide a continuous passagewayfor receiving a pull cable A. The bore 4 of each form-part 1 has aninside dimension which corresponds to the outside dimension of thesupport tube C. As shown by way of example in FIGS. 7 to 10, the bores 4of the form-parts 1 may also have different configuration, with FIG. 7showing a form-part 1 with opposite convex support surfaces 2A, 3A, withFIG. 8 showing a ball-shaped form-part 1, with FIG. 9 showing aform-part 1 with concave support surfaces 2B and 3 and cylindrical bore4, and with FIG. 10 showing a form-part 1 with flat end faces 2C, 3C andcylindrical bore 4.

Suitably, the form-parts 1 are so configured that one of the end faces2, 3 has a concave configuration and the other one of the end faces hasa convex configuration. It is also possible to alternate a first type ofform-parts having convex end faces with a second type of form-partshaving concave or ring-shaped end faces, whereby the inside dimension ofthe first type of form-parts corresponds to the cross section of thetube C while the bore 4 of the second type of form-parts has an insidedimension which exceeds the cross section of the tube C.

As shown in FIG. 1, the form-part 1 may also be provided with a centralrecess 5 to exhibit a free space. If the pull cable A is drawn, thecompensating support casing made from the joined threaded form-partsdoes not press against the cable A to realize a smooth transmission. Theform-parts 1 may be made of metal, in particular of anodized aluminum,but can also be made of ceramic or plastic material that hasadvantageously been shaped to the form-parts 1 by injection moulding.

In order to improve their handling, the individual form-parts 1 shouldbe threaded onto a smooth plastic tube to realize a continuous strand,which is of advantage with respect to easy handling and marketing. Also,the joined form-parts 1 may be additionally covered by a hose (notshown) to realize a stable and bendable unit.

FIGS. 4 and 5 show a further embodiment of a pull cable system whichdiffers from the embodiment of FIGS. 1 to 3 in the configuration of thepassageway 4. Each form-part 1 has on one end face 3 formed as a pan forreceiving the adjacent, approximately ball-shaped end face of anadjoining form-part 1. The form-parts 1 are provided with free spaces 5a, 5 b for enabling a continuous course of the support tube C along acurved path.

FIG. 6 is a general illustration of another embodiment of a pull cablesystem according to the present invention, including form-parts 1 withcylindrical collar 12.

The form-parts 1 may be made of glidable material. It is alsoconceivable to omit the provision of the support tube C altogether, whenusing form-parts of sufficient length and of glidable material so thatthe cable A for transmitting tensile forces is supported directly by thethroughbore 4 of the form-parts 1.

Another embodiment of the force transmission with little friction is thepartly unsupported arrangement of the pull cable between supportsfastened to a frame assembly, as shown in FIGS. 11, 11.1 and 11.2. Forthe deflection of force (disposition of curves), the pull cable A isguided over attachable ball or roller bearings of a curve segment 20 ofthe frame assembly. Two types of bearings may be used: the rollerbearing 23 or the ball bearing 24. Both show an only small loss of forcedue to minimized friction.

Another way of disposing the pull cable with minimized friction valuesmay be achieved by disposing the pull cables A diagonally in a frametube or assembly 25 which extends between a cable inlet fitting 25.1 anda cable outlet fitting 25.2, as shown in FIGS. 12, 12.1 and 12.2. Thiscan also be achieved by retrofitting, i.e., by arranging one or more(plastic) tube/tubes from the cable inlet 25.1 to the cable outlet 25.2and by gluing them to the outlets at the respective end face such thatthe cable A is easy to be disposed in order to traverse the tube 25diagonally, so as to leave the end of the tube without friction orcontact via the cable outlet 25.2. Thus, there will not be any contactwith the tube. This method has the advantage that neither a noisystriking of the cable A against the frame tube 25 nor increased frictionvalues will occur.

As shown in FIG. 13, the curve segment 20 is further provided with asliding and support ring 22 positioned between the cable A and therollers 24 and having a groove for receiving the cable A. A cover cap21.2 envelops around the cable A and the ring 22 and is attached to thecurve segment 20. The ring 22 is also formed with a groove for receivingthe cable A and has an inside diameter equal to the sum of inner radiusof the running surface 24.1 of the segment 20 and the diameter of theball 24.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:
 1. A flexible tensile forcetransmitting cable system, comprising: an axially movable cable fortransmitting a tensile force; a flexible tube for receiving said cablefor axial movement of said cable therein; and a casing surrounding saidtube for absorbing a pressure force, said cable being axially movablerelative to said tube and said casing, said casing including a pluralityof form-parts joined to one another to form a continuous axialpassageway defined by an inside dimension of varying diameters, saidform-parts having abutting end faces between adjacent form-parts withcomplementary configurations enabling dispositions of said casing alongarcuate paths, said form-parts being stringed on and traversed by saidtube, said tube having an outside diameter that is equivalent to asmallest inside diameter of said form-parts.
 2. The cable system ofclaim 1, wherein, for each of said form-parts, one of said end facesthereof has a concave configuration and the other one of said end facesthereof has a convex configuration.
 3. The cable system of claim 1,wherein a first set of said form-parts is alternately joined to a secondset of said form-parts, said first set of form-parts having oppositeconvex end faces, said second set of form-parts having opposite endfaces, each having one of a concave shape and an annular shape.
 4. Thecable system of claim 3, wherein each of said first set of form-partshas an inside dimension corresponding to a cross section of said tube,said passageway in said second set of said form-parts having an insidedimension exceeding said cross section of said tube.
 5. The cable systemof claim 1, wherein said tube is made of plastic.
 6. The cable system ofclaim 1, wherein said form-parts are made of a material selected fromthe group consisting of plastic and ceramic.
 7. The cable system ofclaim 1, wherein fittings secure said casing at opposite ends of a frameassembly.
 8. A flexible tensile force transmitting cable system,comprising: a cable for transmitting a tensile force; a flexible tubefor accommodating the cable; and a casing surrounding said tube forabsorbing a pressure force, said cable being axially movable relative tosaid tube and said casing, said casing including a plurality ofform-parts joined to one another to form a continuous axial passagewaydefined by an inside dimension of varying diameters, said form-partshaving abutting end faces between successive form-parts withcomplementary configurations enabling dispositions of said casing alongan arcuate path, said tube having an outside dimension corresponding toan inside dimension of the passageway, each of said form parts having aninterior recess forming a section of said axial passageway with aninterior dimension with a diameter exceeding that of the tube forcreating a space for compensatory movement of said tube within saidaxial passageway when the cable therein transmits a tensile force. 9.The cable system of claim 8, wherein said form-parts have opposite endfaces, one of the end faces thereof has a concave configuration and theother one of said faces thereof has a convex configuration.
 10. Thecable system of claim 8, wherein a first set of the form-parts isalternately joined to a second set of the form-parts, with said firstset of form-parts having opposite end faces of convex configuration, andwith said second set of form-parts having opposite end faces of aconfiguration selected from the group consisting of a concave shape andan annular shape.
 11. The cable system of claim 8, wherein said tube ismade of plastic.
 12. The cable system of claim 8, wherein saidform-parts are made of a material selected from the group consisting ofglidable plastic and ceramic.
 13. A pull cable system, comprising: acable for transmitting a tensile force; and a casing surrounding saidcable for absorbing a pressure force, said cable being axially movablerelative to said casing, said casing being composed of a plurality ofform-parts joined to one another in end-to-end disposition to form acontinuous axial passageway, each of said form-parts having acircumferential cylindrical collar centrally located thereon, saidform-parts having abutting end faces between successive form-parts withcomplementary configurations enabling dispositions of said casing alongan arcuate path, said axial passageway defined by varied insidedimensions.